_N_e_w_s _f_o_r _p_a_c_k_a_g_e '_p_o_m_p'

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._8:

        • The ‘err()’ and ‘warn()’ C-level macros have been redefined
          to forestall problems that would arise when these macros are
          included in C++ code under forthcoming versions of R.

        • More changes in C codes to forestall issues detected by
          ‘rchk’.

        • Minor corrections to documentation.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._7:

        • Minor corrections to documentation.

        • Changes in some C codes to avoid issues detected by ‘rchk’.

        • Fixed bug in ‘wquant’ introduced by changes in ‘pbeta’ with R
          version 4.3.3.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._6:

        • Minor corrections to documentation.

        • C-level functions ‘set_pomp_userdata’ and
          ‘unset_pomp_userdata’ are no longer exported.

        • ‘bspline_eval’ is no longer exported.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._5:

        • There is now access to ordinary B-spline basis functions (and
          their derivatives) at the C snippet level.  It will still
          almost always be preferable to construct a spline basis once
          and pass it to ‘pomp’ functions as part of a
          ‘covariate_table’, but this functionality may occasionally be
          useful.

        • ‘bspline_eval’ is now deprecated as part of the ‘pomp’ C API.

        • The formatting of some printed messages has been modified to
          forestall warnings in the latest R-devel.

        • Stateful objective functions (class ‘objfun’) now behave as
          if they are ‘pomp’ objects.

        • C-level functions ‘set_pomp_userdata’ and
          ‘unset_pomp_userdata’ are deprecated.  The latter now
          generates a warning.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._4:

        • ‘stew’ now returns timing information by default.

        • The spurious warnings associated with NULL ‘userdata’ have
          been eliminated.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._3:

        • The new option ‘on_load’ allows one to specify a C snippet
          that will be executed at the time the C snippet library is
          loaded.

        • Internally, the ‘userdata’ are made available via calls to
          ‘pompLoad’ rather than within each call to a ‘pomp’
          workhorse.

        • The data frames returned by ‘cond_logLik’ and
          ‘eff_sample_size’ when ‘format="data.frame"’ have been
          improved.  In particular, they contain (as variable ‘time’)
          the times (rather than the index of the time vector as
          before).

        • Changes to the report generated by ‘spy’.

        • Some documentation improvements.

        • The manual pages have been reorganized, with improved
          cross-linking.

        • A bug in ‘filter_traj’ etc. arising when not all state
          variables have names was fixed.

        • This version adds the new basic component ‘dinit’ for
          evaluating the probability density function of the
          initial-state distribution.  There is a corresponding
          workhorse function, ‘dinit()’.

        • The constructor ‘pomp’ now takes the optional argument
          ‘nstatevars’, which can be used to increase the dimension of
          the latent state-vectors created by ‘rinit’.  By default,
          ‘nstatevars = length(statenames)’, and ‘nstatevars’ can only
          be used to _increase_, not to decrease, the dimension of the
          latent state process.  Moreover, ‘nstatevars’ has no effect
          if the ‘rinit’ basic component is furnished as an R function.

        • Name checking on internally-created vectors and arrays is
          less strict than previously.  In particular, it is possible
          to have variables without names (i.e., ‘""’).

        • ‘reulermultinom’ now returns ‘NA’ rather than ‘NaN’, in
          keeping with the behavior of ‘rbinom’.  Thanks to John Drake
          for calling attention to this issue.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._2:

        • A bug in ‘stew’ resulting in namespace conflicts has been
          repaired.

        • We no longer import directly from ‘tidyverse’ functions.
          This reduces the list of packages upon which ‘pomp’ depends
          from 20 to 5.  This does introduce a dependency on the
          ‘data.table’ package.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _5._1:

        • When the archive directory does not exist, ‘bake’ and ‘stew’
          now create it.

        • We no longer import from ‘plyr’.

        • The ‘dimnames’ attributes of various arrays that appear in
          ‘pomp’, including arrays of observables, state variables,
          parameters, covariates, and so on, have been made uniform.
          In particular, when a dimension of an array corresponds to
          variables with different names, this dimension is itself
          named “name”.  Previously, its name was sometimes “variable”
          and sometimes “parameter”.  This change is meant to
          streamline interaction with the ‘tidyverse’.

        • Some minor bugfixes.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._7:

        • Functions with names.that.contain.dots that have been
          deprecated since version 4.5.1 are now defunct.  Attempts to
          use such functions will generate an error with a message
          indicating the replacement function.

        • ‘plot’ now removes ‘NA’.

        • Better handling of ‘listie’s (lists of ‘pomp’ objects).

        • New ‘concat’ function to turn lists of ‘pomp’ objects into
          ‘listies’.

        • Bug fix in ‘filter_traj’ applied to ‘pfilterList’ and
          ‘pmcmcList’ objects.

        • The ‘states’ and ‘obs’ methods take a new optional argument,
          ‘format’.  Setting ‘format="data.frame"’ causes the method to
          return the states or data in a convenient data-frame format.

        • When ‘melt’ is applied to a list, the identifier variable is
          now “‘.Lx’”, where ‘x’ denotes the level.  This applies when
          ‘as.data.frame’ is used to coerce a list of ‘pomp’ objects,
          and when ‘saved_states’ is used to extract the particles from
          a list of ‘pfilterd_pomp’ objects.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._6:

        • ‘logmeanexp’ can now compute the effective sample size, which
          can be useful in determining the reliability of its estimate.
          To do so, set ‘ess=TRUE’ in a call to ‘logmeanexp’.

        • ‘logmeanexp’ now returns a fully-named vector when either
          ‘se=TRUE’ or ‘ess=TRUE’.

        • A new ‘format’ argument has been added to the extractor
          functions ‘cond_logLik’, ‘eff_sample_size’, ‘filter_mean’,
          ‘filter_traj’, ‘forecast’, ‘pred_mean’, ‘pred_var’, and
          ‘saved_states’.  This allows the user to extract the relevant
          elements in data-frame format if desired.

        • ‘pomp’ no longer depends on the superseded package
          ‘reshape2’.  The ‘melt’ function for converting arrays and
          nested lists into data frames is accordingly no longer
          re-exported from ‘reshape2’.  It has been replaced by a
          stricter version of ‘melt’.

        • The ‘magrittr’ pipe ‘%>%’ is no longer re-exported by ‘pomp’:
          use the native R pipe ‘|>’ instead.

        • The package now requires R version 4.1 at least.

        • All ‘pomp’ functions with names.that.contain.dots have been
          deprecated in favor of functions in ‘snake_case’.  This is to
          avoid anticipated problems with CRAN checks, which (falsely)
          assume that certain functions with dotted.names are S3
          methods.  From this point, no exported ‘pomp’ function has
          such a name.

        • The ‘dimnames’ attributes for some of the arrays computed in
          ‘pfilter’ and ‘pmcmc’ computations have changed.  In
          particular, whereas in previous versions, the ‘time’
          dimension was given names that were character strings
          composed of decimal representations of the time (difficult to
          work with and prone to roundoff error), the ‘time’ dimension
          now is not given names.

        • A bug that resulted in ‘gompertz’ giving different
          simulations on Windows machines has been fixed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._5:

        • A bug in trajectory computation for maps (discrete-time
          dynamical systems) has been fixed.  Thanks to Felicia
          Magpantay for noticing it and tracking it down.

        • Minor documentation improvements.

        • The weighted quantile function ‘wquant’ now uses the
          Harrell-Davis estimator instead of the type-7 estimator used
          previously.  This eliminates bugs associated with non-integer
          weights.

        • It is now possible to retrieve the weighted particles
          computed in the course of a ‘pfilter’ computation.  To
          accomplish this, set ‘save.states="weighted"’ in the call to
          ‘pfilter’ and retrieve the particles and their weights using
          ‘saved.states’.  Previously, one could obtain only the
          unweighted particles.

        • Some documentation improvements.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._4:

        • The new function ‘wquant’ computes weighted quantiles.

        • The precise order in which the ‘pmcmc’ function computes
          prior and likelihood of furnished and proposed parameters has
          changed slightly.  This prevents proposals that are
          incompatible with the prior from being passed to ‘pfilter’
          and forestalls an associated class of errors.  A consequence
          of this change, ‘pmcmc’ computations using the new version
          will differ very slightly from previous computations, even
          with the RNG seed fixed at its previous values.

        • There is now a C interface to the ‘bspline_eval’ function.
          See the ‘pomp’ C API documentation for details.

        • The ‘bspline.basis’ function now takes the optional argument
          ‘rg’ which allows one to specify the range over which the
          basis will be constructed.  By default, this is ‘range(x)’,
          which agrees with the behavior in earlier versions.

        • Documentation improvements.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._3:

        • The archiving functions ‘bake’ and ‘stew’ now use a slightly
          less exacting comparison of the expression, ‘expr’, they are
          furnished.  *NB:* Running ‘bake’ or ‘stew’ with archives
          created by earlier versions may result in recomputation.

        • The ‘time’ method has been extended to ‘pompList’ and related
          objects.

        • All workhorse functions except ‘partrans’ have new default
          arguments.

        • Some documentation improvements.

        • The archiving functions ‘bake’ and ‘stew’ now take the
          argument ‘dir’, which is the directory holding the archive
          files.  By default, this is the current working directory or
          the value of the global option ‘pomp.archive.dir’.

        • A new global option, ‘pomp_archive_dir’, can be used to
          specify the locations of archive files used by ‘bake’ and
          ‘stew’.

        • Documentation repair of issue flagged by Kurt Hornik (9 June
          2022).

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._2:

        • Minor changes, invisible to the user.

        • Minor changes to the C codes to keep up with R-devel.

        • Minor changes in the implementation of ‘bake’ and ‘stew’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._1:

        • Change in the names of the variables returned by
          ‘as.data.frame’ applied to a ‘pfilterd.pomp’ object.

        • Fixed bug found by Jesse Wheeler and Ed Ionides, to do with
          `simulate()` with `include.data=TRUE`.

        • It is now possible to plot lists of ‘pomp’ and ‘pomp’-derived
          objects using a single call to ‘plot’.

        • The ‘rbetabinom’ and ‘dbetabinom’ functions, long present as
          part of the C API, are now available as R functions.

        • The SIR examples ‘sir()’ and ‘sir2()’ now use a negative
          binomial measurement model.

        • ‘parmat’ can now take a data frame of parameters and convert
          it into a matrix suitable for furnishing to the ‘params’
          argument of any ‘pomp’ function.

        • It is now possible to change the parameters in an ‘objfun’
          (objective function) object using ‘coef(object)<-value’.

        • ‘parmat’ now takes an optional argument, ‘names’, which
          allows the user to name the parameter sets.

        • Independent realizations of the stochastic processes modeled
          in ‘pomp’ are now distinguished by different values of ‘.id’.
          This behavior is now uniform throughout.

        • ‘bake’ and ‘stew’ now send messages instead of warnings when
          they recompute an archive due to a change in code or
          dependencies.

        • It is now possible to change the parameters in an ‘objfun’
          (objective function) object using ‘coef(object)<-value’.

        • The ensemble adjusted Kalman filter (‘eakf’) has been
          refactored.  It now makes use of the ‘emeasure’ and
          ‘vmeasure’ basic components to compute an approximation of
          the linear relationship between the latent state and the
          observed variables.

        • The ‘forecast’ method now works for ‘pfiterd_pomp’ objects
          (i.e., results of ‘pfilter’, ‘pmcmc’, or ‘mif2’
          computations).

        • Two new basic model components have been introduced.  These
          are:

          emeasure, which computes the expectation of the observable
              variables conditional on the latent state;

          vmeasure, which computes the covariance matrix of the
              observables given the latent state.

          These are used by the newly refactored ensemble Kalman
          filter, ‘enkf’.

        • The basic (linear, Gaussian) Kalman filter is now available
          as ‘kalmanFilter’.

        • Computation of Monte Carlo-adjusted profile likelihood is now
          facilitated by the new ‘mcap’ function.

        • The default return-value format for ‘trajectory’ now matches
          that of ‘simulate’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _4._0:

     Version 4 contains a few changes that are not backward compatible.
     These are all to do with the elementary function ‘trajectory’,
     which computes trajectories of the deterministic dynamical
     skeleton.  See below for details.

        • The behavior of ‘trajectory’ now fully conforms to the
          behavior of other ‘pomp’ elementary functions.  In
          particular, one can now add, remove, or modify basic model
          components in a call to ‘trajectory’ just as one can with
          ‘simulate’, ‘pfilter’, ‘probe’, etc.  Before version 4,
          additional arguments to ‘trajectory’ (i.e., those passed via
          ‘...’) were passed on to the ODE integrator in the case of
          continuous-time deterministic skeletons (i.e., vectorfields)
          and ignored in the case of discrete-time skeletons (i.e.,
          maps).  As of version 4, in order to adjust ODE integrator
          settings it is necessary to use the ‘ode_control’ argument of
          ‘trajectory’.  This behavior matches that of ‘traj_objfun’.

        • It is now possible to create a ‘pomp’ object from scratch
          using ‘trajectory’, together with a specification of the
          rinit and skeleton components.  Prior to version 4, in order
          to do so, it was necessary to first create a dummy data set,
          then call ‘pomp’, and then pass the resulting ‘pomp’ object
          to ‘trajectory’.  This can now be achieved in one call.

        • The user now has the option, in a call to ‘trajectory’, to
          have the results returned as one or ‘pomp’ objects.  In this
          regard, its behavior matches that of ‘simulate’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._6:

        • The ‘states’ and ‘obs’ methods now work for lists of ‘pomp’
          objects (‘listies’).

        • The workhorse function ‘flow’ now has default arguments.

        • The stateful objective function created by ‘traj_objfun’ has
          been refactored so that it is independent of ‘trajectory’.
          This change is invisible to the user, but lays the groundwork
          for future changes in ‘trajectory’.

        • Stateful objective functions created by ‘traj_objfun’,
          ‘nlf_objfun’, ‘probe_objfun’, and ‘spect_objfun’ now have
          default arguments.  In particular, the default is argument is
          a zero-length numeric vector.  Calling such a function with
          no arguments is valid if and only if the objective function
          was created with no variables to estimate (empty ‘est’).

        • Fixed bug in ‘rprior’ arising with integer-valued return
          vectors.

        • Major improvements to the package manual, including richer
          cross-linking and better organization.

        • When ‘simulate’ is called with ‘format="data.frame"’ and
          ‘include.data=TRUE’, the interpolated covariates are now
          included in the data frame that is returned.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._5:

        • ‘bake’ takes a new option, ‘timing’, that controls whether
          information on the timing is returned or merely stored.  By
          default, this is set to ‘TRUE’, though this default behavior
          may change in future.

        • When they encounter an archive produced by an older version,
          ‘bake’ and ‘stew’ now update the archive in the new format.
          Recomputation should never be triggered in this case: If
          recomputation is desired, delete the archive file.

        • ‘bake’ and ‘stew’ now archive a digest of the code in ‘expr’
          and on subsequent calls check to see if the archived version
          matches the current version.  Thus, changes to the code
          automatically trigger recomputation.

        • ‘bake’ and ‘stew’ take the new argument ‘dependson’.  Using
          this argument, the user can specify objects upon which the
          computation depends.  These should be passed as unquoted
          variables; if there are multiple dependencies, they can be
          passed using ‘c’ or ‘list’.  Digests of these objects will be
          archived and checked against current values on subsequent
          calls.  Thus, changing any dependency will automatically
          trigger recomputation.

        • ‘bake’ now archives the information pertinent to the ‘bake’
          call; this information is no longer returned along with the
          result of the computation (unless ‘info=TRUE’).  Similarly,
          ‘stew’ stores a list, “.ingredients”, in the file it creates.
          In the ‘stew’ case, unlike all the other objects that are
          created by ‘expr’, this list is _not_ by default loaded into
          the calling environment (e.g., the user's workspace).  It
          will be loaded if the ‘info’ flag is set to ‘TRUE’.

        • ‘freeze’ no longer stores the details of the RNG seed and
          kind as an attribute of the returned object.

        • Fix bug in ‘bsmc2’ arising when some particles have zero
          likelihood.  This is Issue #152.  Thanks to Hola-Kwame
          Adrakey for reporting it.

        • It is now possible to call ‘partrans’ directly on an
          objective function, such as those created by ‘traj_objfun’,
          ‘nlf_objfun’, ‘probe_objfun’, or ‘spect_objfun’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._4:

        • The package manual and help pages has been streamlined.

        • The ‘mif2’ diagnostic plots have been made more flexible.

        • Some deprecated functions have been removed.  These include
          ‘cond.loglik’, ‘sliceDesign’, ‘runifDesign’, ‘sobolDesign’,
          and ‘profileDesign’, which have been replaced by
          ‘code.logLik’, ‘slice_design’, ‘runif_design’,
          ‘sobol_design’, and ‘profile_design’, respectively.

        • A bug in ‘rgammawn’ has been fixed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._3:

        • The ‘pomp’ C API has been expanded a bit, to facilitate other
          packages' linking to the ‘pomp’ library.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._2:

        • The help pages have been improved, with an description of the
          overall package structure and pages on basic model
          components, elementary algorithms, and estimation algorithms.

        • A note to Windows users on avoiding certain C snippet
          compilation errors has been added to the help pages.

        • The behavior of ‘profile_design’ has changed.  Previously,
          the same random (or sub-random) sequence was used for all
          non-profile parameters.  Now, for each profile slice, a
          distinct set of points is generated.

        • ‘profileDesign’, ‘sliceDesign’, ‘runifDesign’, and
          ‘sobolDesign’ have been deprecated and will be removed in a
          future release.  They are replaced by ‘profile_design’,
          ‘slice_design’, ‘runif_design’, and ‘sobol_design’,
          respectively.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _3._1:

        • A new ‘saved.states’ method allows one to extract the saved
          states from a particle filter computation.

        • All instances of ‘cond.loglik’ have been changed to
          ‘cond.logLik’, to remove a common source of typographical
          error.

        • A new sequential importance sampling algorithm has been
          implemented as ‘wpfilter’.  This is a generalization of the
          algorithm in ‘pfilter’ in that it tracks the weights of the
          particles and allows the user to customize the resampling
          scheme.

        • In ‘mif2’, the specification of particle numbers, ‘Np’, has
          changed.  When ‘Np’ is supplied as a function, ‘Np(0)’ is the
          requested number of particles at the beginning of the time
          series.  The previous behavior was that ‘Np(1)’ specified the
          requested number of particles.  This behavior now matches
          that of the other particle filtering algorithms, ‘pfilter’,
          ‘bsmc2’, and ‘pmcmc’.

        • ‘bsmc2’ can now accept a variable number of particles, as do
          the other particle-filter based algorithms ‘pfilter’,
          ‘pmcmc’, and ‘mif2’.

        • The internal ‘systematic_resample’ function now allows the
          user to specify the number of samples desired.  Previously,
          these were always equal to the number of weights supplied.

        • As promised from version 2.4.1, the ‘tol’ and ‘max.fail’
          arguments have been removed completely from all
          particle-filtering algorithms, including ‘pfilter’, ‘pmcmc’,
          ‘bsmc2’, and ‘mif2’.  See the ‘pomp’ news blog
          (<https://kingaa.github.io/pomp/blog.html>) for more
          information.

        • The long-deprecated functions ‘onestep.dens’, ‘onestep.sim’,
          ‘discrete.time.sim’, ‘euler.sim’, ‘gillespie.sim’,
          ‘gillespie.hl.sim’, ‘conv.rec’, and ‘values’ have been
          removed.  These have been replaced as follows

            ‘onestep.dens’       direct specification of ‘dprocess’ component 
            ‘onestep.sim’        ‘onestep’                                    
            ‘discrete.time.sim’  ‘discrete_time’                              
            ‘euler.sim’          ‘euler’                                      
            ‘gillespie.sim’      ‘gillespie’                                  
            ‘gillespie.hl.sim’   ‘gillespie_hl’                               
            ‘conv.rec’           ‘traces’                                     
            ‘values’             ‘as.data.frame’ or ‘as(x,"data.frame")’      
           
        • Trap error from non-finite likelihoods in ‘pmcmc’.

        • New test of ‘pmcmc’ codes in ‘tests/issue109.R’.

        • Trap error from missing accumulator variables in
          ‘trajectory’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._8:

        • As promised, the default value of ‘tol’ in the
          particle-filtering algorithms ‘pfilter’, ‘pmcmc’, ‘mif2’, and
          ‘bsmc2’ has been changed to zero.  A warning continues to be
          issued if ‘tol’ is set to anything other than 0.  In a future
          release, the option to choose a nonzero tolerance will be
          removed entirely.

        • The Euler step size in ‘sir’ is now adjustable.

        • In traces and diagnostic plotting methods, the ‘nfail’
          variable (tracking numbers of filtering failures) has been
          dropped.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._7:

        • Another documentation bug was fixed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._6:

        • A documentation bug, identified by K. Hornik, was fixed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._5:

        • In anticipation of forthcoming algorithmic changes, the ‘tol’
          and ‘max.fail’ arguments of ‘pfilter’, ‘bsmc2’, ‘pmcmc’, and
          ‘mif2’ are now deprecated.  A warning is issued if ‘tol’ is
          set to anything other than 0.  In a future release, these
          options will be removed entirely: the behavior will be
          similar to that obtained in the present release by setting
          ‘tol=0’.

        • A new example illustrating the ‘accumvars’ argument has been
          provided.

        • Internal computations now use increased precision for means,
          variances, and certain calculations with likelihoods.

        • A new help page, ‘pomp_examples’, lists the various example
          datasets and pomp objects provided with the package.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._4:

        • The source codes underlying specification of basic model
          components via R functions has been reworked to remove
          reliance on deep ‘PROTECT’ stacks.  Thanks to Thomas Kalibera
          for showing the way!

        • A bug in the documentation for ‘filter.traj’, pointed out by
          Pierre Jacob, has been fixed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._3:

        • The C API for ‘pomp’ is no longer explained only in comments
          in the “pomp.h” header file.  It is now described and
          explained in the new C API vignette.

        • The new ‘pomp_cdir’ global option allows one to set the
          directory holding C snippet files globally.

        • A bug caused by re-use of the ‘cfile’ argument has been
          fixed.  Re-use now triggers an error, with an informative
          message.

        • Some documentation improvements.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._2:

        • A bug in ‘runifDesign’ (and therefore ‘profileDesign’ when
          ‘type="runif"’) has been fixed.

        • There are now ‘plot’ methods for objects of classes
          ‘probe_match_objfun’ and ‘spect_match_objfun’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _2._1:

        • The ‘melt’ function can now be applied to arbitrary ‘pomp’
          objects.

        • A new function, ‘runifDesign’ allows construction of design
          matrices using samples from multivariate uniform
          distributions.

        • The ‘profileDesign’ function takes a new argument, ‘type’,
          with two options: ‘"sobol"’, the default, constructs the
          design using ‘sobolDesign’, as before.  ‘"runif"’ uses the
          new ‘runifDesign’ function.

        • A new example, comprising models and data for the 2014--2016
          west African Ebola virus disease outbreak, is included.  See
          ‘?ebola’ for details.

        • It is now possible to adjust the observation times and
          zero-time in the ‘sir’ and ‘sir2’ examples.  One can also
          change the default RNG seed used in generating the simulated
          data.

        • The codes underlying the ‘rprocess’ workhorse have been
          streamlined to obviate an unnecessary copy operation.  As a
          result, the interface to the ‘rprocess’ workhorse has been
          changed.

        • The interface to the new ‘flow’ workhorse has been changed to
          match.

        • The new ‘flow’ workhorse allows integration/iteration of the
          deterministic skeleton at arbitrary times from an arbitrary
          initial condition.

        • When ‘coef’ is applied to a ‘listie’, the result can be more
          usefully ‘melt’ed.

        • The probe-names returned by ‘probe.acf’ and ‘probe.ccf’ have
          changed.

        • A bug, whereby the ‘coef’ method from other packages was
          masked, has been fixed.

        • Errors in the documentation have been corrected.

        • There is a new ‘as.data.frame’ method for ‘listie’s.

        • Some problems with the exposure of internal objects for
          package developers have been corrected.

        • The ‘magrittr’ pipe operator, ‘%>%’, is now re-exported.

        • More examples have been included.

        • Minor changes to error messages.

        • The names of the ‘objfun’ methods have been changed to
          ‘probe_objfun’, ‘spect_objfun’, ‘traj_objfun’, and
          ‘nlf_objfun’.

        • The package directory structure has been modified to include
          a new ‘examples’ directory, which holds the examples used in
          the documentation.

        • The names of the ‘objfun’ methods have been shortened.

        • It is now permissible that the sequence of observation times
          (and sequences of covariate times) be merely non-decreasing
          sequences.  Previously, ‘pomp’ insisted on strictly
          increasing time sequences.

        • The default cooling schedule (‘cooling.type’) in ‘mif2’ is
          now “geometric”, in contrast to “hyperbolic”, as before.

        • ‘pomp’ now requires at least R version 3.5.

        • The ‘zeronames’ argument has been renamed ‘accumvars’.

        • In the course of ordinary work, one should never need to
          interact with the low-level ‘pomp’ constructor function now.

        • The ‘pompExample’ function has been dropped.  The various
          examples are now included as regular functions that construct
          ‘pomp’ objects.

        • The ‘bbs’ example has been dropped.

        • One can now modify basic model components at (almost) any
          stage in a pipeline of ‘pomp’ computations.  All the
          top-level inference functions, plus ‘probe’, ‘pfilter’, and
          ‘simulate’ now allow modification of basic model components.

        • The ‘rprocess’ plugins ‘onestep.sim’, ‘discrete.time.sim’,
          ‘euler.sim’, ‘gillespie.sim’, and ‘gillespie.hl.sim’ have
          been renamed ‘onestep’, ‘discrete_time’, ‘euler’,
          ‘gillespie’, and ‘gillespie_hl’, respectively.  The old usage
          is available but deprecated.

        • One can now call ‘simulate’ on a model without reference to
          any data.

        • The covariate table facility (‘covariate_table’) now supports
          piecewise constant interpolation.

        • The syntax with which one includes covariates via
          ‘covariate_table’ has become more flexible.  Specifically,
          the arguments to ‘covariate_table’ are now evaluated
          sequentially, so that later ones can depend on earlier ones.
          Once evaluated, the covariates are bound column-wise into a
          single data frame.

        • The manner in which one writes R functions to specify basic
          model components has been totally changed.  Before, one wrote
          functions that took specific arguments such as 'x', 'params',
          and 'covars'.  Now, one writes such functions with any or all
          state variables, observables, covariates, and/or time as
          arguments.

        • ‘simulate’ now returns more informative results when
          simulations from multiple parameter sets are simultaneously
          computed.  Specifically, if ‘params’ has column names, these
          are used to identify the resulting simulations.  Thus when
          ‘format = "pomps"’ (the default), the names of the resulting
          list will be constructed from the column names of ‘params’.
          Likewise, when ‘format = "arrays"’, the resulting arrays will
          have informative column names; When ‘format = "data.frame"’,
          the identifier variable will make use of the column names.

        • The basic particle filter, ‘pfilter’, has a simpler mode of
          operation: ‘params’ should be a single parameter set only.
          That is, it is no longer possible to pass a matrix of
          parameters to ‘pfilter’.

        • The Liu-West algorithm, ‘bsmc2’, has a simpler mode of
          operation: ‘params’ should be a single parameter set only:
          the SMC particles are drawn from ‘rprior’.

        • The ‘as.data.frame’, ‘states’, and ‘obs’ options for
          ‘simulate’ have been done away with.  One now chooses the
          format of the returned simulations via the ‘format’ argument.
          When one simulates at multiple parameter sets, list names,
          array ‘dimnames’, or identifying variables in the output data
          frame help to correlate simulations with parameter sets.

        • The ‘as.data.frame’ argument to ‘trajectory’ has been removed
          in favor of a new ‘format’ argument that allows one to choose
          between receiving the results in the form of an ‘"array"’ or
          a ‘"data.frame"’.

        • All the basic model components now have defaults.

            • The default ‘rinit’ behavior remains as it was: it
              assumes the initial state distribution is concentrated at
              a point mass determined by parameters with “‘.0’” or
              “‘_0’” suffices.

            • The default process model is “missing”: calls to
              ‘dprocess’ and ‘rprocess’ will result in missing values
              (‘NA’).

            • The default measurement model is “missing” as well.

            • The default prior is flat and improper: all calls to the
              default ‘dprior’ result in ‘1’ (‘0’ if ‘log = TRUE’, and
              all calls to ‘rprior’ result in ‘NA’.

            • The default skeleton is missing.

            • The default parameter transformations remain the
              identity.

        • The ‘transform’ argument present in many ‘pomp’ algorithms
          has been removed.  Parameter transformations are now
          automatically performed when appropriate.  The default
          parameter transformation remains the identity.

        • The old ‘probe.match’ and ‘traj.match’ functions have been
          removed.  The new approach to parameter estimation based on
          numerical optimization involves constructing stateful
          objective functions.  There are now three of these:
          ‘traj.match.objfun’, ‘probe.match.objfun’, and
          ‘spect.match.objfun’.

        • The documentation system has been thoroughly overhauled.

        • In ‘skeleton’, the ‘t’ argument has been replaced by ‘times’,
          to make this uniform with the other workhorse functions.

        • Covariates are now included using the ‘covariate_table’
          construction, passed via the ‘covar’ argument to ‘pomp’.  The
          ‘tcovar’ argument is no longer used.

        • Instead of providing separate ‘fromEstimationScale’ and
          ‘toEstimationScale’ arguments to ‘pomp’, one now provides a
          single ‘partrans’ argument constructed by means of the new
          function ‘parameter_trans’.  In addition, references to
          “fromEstimationScale” and “toEstimationScale” have been
          abbreviated to “fromEst” and “toEst”, respectively,
          throughout the package.

        • When writing C snippets for parameter transformations, the
          notation ‘T_p’ refers to the value of ‘p’ on the estimation
          scale.  Thus, if parameter alpha is to be log-transformed for
          estimation, the ‘toEst’ snippet would contain the line
          ‘T_alpha = log(alpha);’ and the ‘fromEst’ snippet would
          include ‘alpha = exp(T_alpha);’.

        • The ‘parameter_trans’ function now takes optional arguments
          ‘log’, ‘logit’, and ‘barycentric’, with names of parameters
          to be log-, logit-, and log-barycentric transformed,
          respectively.

        • The ‘measurement.model’ argument to ‘pomp’ has been removed.
          It is now necessary to specify the measurement model directly
          using ‘rmeasure’ and/or ‘dmeasure’.

        • The ‘initializer’ is no longer referred to by that name.  It
          is now ‘rinit’, since it draws from the distribution of the
          latent state at the initial time.  The low-level function
          ‘init.state’ has been replaced by ‘rinit’.

        • The ‘conv.rec’ method has been deprecated, replaced by the
          new ‘traces’ method.

        • The ‘euler.sir’ example has been renamed ‘sir’.

        • The ‘gillespie.sir’ example has been renamed ‘sir2’.

        • The ‘covmat’ method can now be applied to a ‘probed.pomp’
          object.  It returns the estimated covariance matrix of the
          probes.

        • When ‘trajectory’ calls on ‘deSolve’ routines to numerically
          integrate a model vectorfield, more informative error
          messages are generated, and diagnostics are printed when
          ‘verbose = TRUE’.

        • The ‘show’ method applied to pomp objects is now quite terse.
          To obtain detailed information, the ‘spy’ method is
          available.

        • The ‘spy’ method now returns the information formerly
          displayed in a call to ‘show’, in addition to the C files
          associated with any C snippets.

        • The use of ‘$’ methods to access the slots of ‘pomp’ S4
          objects has now been removed.  These classes are no longer
          exported (for the most part).

        • The ‘transform’ argument to the ‘probe.quantile’ function has
          been removed (as it is entirely redundant!).

        • The old and deprecated ‘mif’ and ‘bsmc’ methods have been
          removed.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_9:

        • The ‘obs’ and ‘states’ arguments of ‘simulate’ are deprecated
          and will be removed in a forthcoming release.

        • The C-level interface for ‘apply_probe_sims’ has changed: the
          new argument ‘rho’ must be the “package:pomp” environment.

        • A bug in ‘pfilter’ (and hence ‘pmcmc’) when
          ‘filter.traj=TRUE’ was discovered and fixed.  In the buggy
          version, the filter trajectory was sampled with incorrect
          weights.

        • Timo Voipio contributed a pull request that traps the error
          resulting from ‘sannbox’ being passed a ‘candidate.dist’ that
          is not a function.

        • ‘show’ and ‘print’ methods have been made very terse: they
          simply report on the class of the object in question.  To see
          more detailed information about a ‘pomp’ object, use ‘spy’.

        • New (unexported) ‘solibs<-’ method allows developers of
          packages extending ‘pomp’ to incorporate C snippets into
          object that contain ‘pomp’ objects.

        • New ‘verbose’ option in ‘trajectory’ gives diagnostic
          information from ‘deSolve’ integration routines.  Of course,
          this is pertinent only if the model skeleton is a
          vectorfield.

        • Bug in the display of ‘istate’ when ‘deSolve::ode’ errors has
          been fixed.

        • New ‘hitch’ function facilitates construction of ‘pomp.fun’
          objects from R functions, C snippets, and links to external
          libraries.

        • Native routines needed to access ‘pomp.fun’ objects in C are
          now registered for use by other packages.

        • ‘coef(object) <- NULL’, where ‘object’ is of class ‘pomp’,
          erases any parameters stored in ‘object’.

        • The ‘euler.sir’, ‘gillespie.sir’, ‘blowflies’, ‘ricker’,
          ‘bbs’, ‘dacca’, and ‘rw2’ examples are all now implemented
          using C snippets.

        • A new ‘pomp_defines.h’ header is provided for developers of
          packages that depend on ‘pomp’.

        • Internally, ‘rprocess’ is no longer stored as an R function.
          The use of plugins is now required for the implementation of
          the ‘rprocess’ component.  Currently, there are five plugins
          available: ‘onestep.sim’, ‘discrete.time.sim’, ‘euler.sim’,
          ‘gillespie.sim’, and ‘gillespie.hl.sim’.

        • The new ‘hitch’ function automates the building and linking
          of C snippets and R functions into ‘pomp.fun’s.

        • The handling of ‘dprocess’ has changed.  The ‘onestep.dens’
          plugin is now deprecated and will soon be removed.
          ‘dprocess’ is now specified directly using either a C snippet
          or an R function, in much the same way that, for example,
          ‘dmeasure’ is specified.

        • The old ‘forward’ and ‘inverse’ options for the ‘dir’
          argument of ‘partrans’ have been dispensed with.  The much
          more descriptive options ‘toEstimationScale’ and
          ‘fromEstimationScale’ remain.

        • The C snippet compiling facilities have been thoroughly
          reworked.

        • ‘onestep.dens’ can now take a ‘Csnippet’ specification of the
          process-model transition density.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_8:

        • All inference functions can now take a list in the ‘start’ or
          ‘params’ arguments.

        • When altering parameters in a call to ‘probe’ on a
          ‘probed.pomp’ object, the new parameters were ignored.  This
          bug has been fixed.

        • ‘mif2’, ‘pfilter’, ‘probe’, ‘probe.match’, and
          ‘probe.match.objfun’ can now gracefully handle a list in the
          ‘start’ or ‘params’ arguments.

        • New ‘spy’ method displays the C snippet file(s) associated
          with a ‘pomp’ object.

        • The long-deprecated ‘seed’ argument to ‘bsmc’ and ‘bsmc2’ has
          been removed.

        • More work to obviate warnings generated by T. Kalibera's
          latest ‘rchk’ checks.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_7:

        • Messages from the compiler resulting from attempts to compile
          C snippets are now suppressed on all platforms except in case
          of failure.  Setting ‘verbose=TRUE’ forces display of these
          messages.

        • Source codes have been revisited to obviate warnings
          generated by T. Kalibera's latest ‘rchk’ checks.

        • Fix a minor bugs in ‘spect’.

        • Improve test coverage.

        • ‘spect.match’ has been refactored, with small changes to the
          interface.

        • ‘pomp’ now handles specification of workhorse functions
          (i.e., ‘rprocess’, ‘dprocess’, ‘rmeasure’, ‘dmeasure’,
          ‘initializer’, ‘skeleton’, ‘rprior’, ‘dprior’,
          ‘fromEstimationScale’, ‘toEstimationScale’) as ‘NULL’ more
          consistently.

        • Fix bug in systematic resampler when ‘np != nw’.

        • Fix bug in ‘conv.rec’ when only one parameter is requested.

        • Correct and improve documentation for ‘conv.rec’.

        • ‘coef<-’ can now take a list of parameters: it simply applies
          ‘unlist’ to turn the list into a numeric vector.

        • Simplify ‘conv.rec’.

        • In ‘pfilter’, ‘Np’ is now a required argument unless ‘params’
          is specified as a matrix of particles.  Thanks to Carles
          Breto for catching the unintended behavior.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_6:

        • The bug reported in issue #57 has been fixed.

        • A bug arising when building pomp objects with Csnippets in
          certain Windows configurations has been fixed.

        • Issue #56, in which covariate names are discarded when
          coercing a pomp object to a data frame, has been fixed.
          Thanks to Eamon O'Dea for reporting this bug.

        • More informative error messages are given when ‘bake’ or
          ‘freeze’ return ‘NULL’.  In such a case, these functions now
          generate a warning and return a character-string message,
          with attributes.

        • Improve documentation of ‘traj.match’, in response to Issue
          #57.

        • A new facility, ‘gillespie.hl.sim’, allows implementation of
          Gillespie's algorithm for exact stochastic simulation of
          continuous-time Markov processes via a streamlined C snippet
          interface.

        • The old facility for Gillespie simulations, ‘gillespie.sim’,
          now accepts C snippets for faster calculation of event rates.

        • The old ‘skeleton.type’ and ‘skelmap.delta.t’ arguments of
          the ‘pomp’ constructor, which have generated error messages
          since version 1.9.2, have been done away with completely.

        • Eamon O'Dea identified a bug (Issue #54) occurring when
          ‘pomp’ is called with a single-row data frame.  This has been
          fixed using his contributed patch.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_5:

        • A new ‘dmultinom’ function is provided in ‘pomp.h’.  This
          provides the probability distribution function for the
          multinomial distribution.

        • Improved tests.

        • Fixed bugs emerging in R-devel due to refactoring of
          underlying R source code.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_4:

        • Eamon O'Dea pointed out that the bug in ‘gillespie.sim’,
          addressed by version 1.12.3, was not completely fixed.  This
          problem has now been resolved.  In addition, covariates are
          now guaranteed to be evaluated at least once per observation
          interval.

        • The new argument ‘hmax’ to ‘gillespie.sim’ allows the user to
          specify the maximum step size that will be taken before
          covariates are evaluated.

        • The K-leap method has been removed.  Its accuracy is low on
          test problems and it is difficult to make it compatible with
          the pomp paradigm.  In particular, it does not readily
          accomodate time-varying covariates in a sensible way, nor
          does it lend itself to simulations at pre-specified times.

        • ‘bspline.basis’ and ‘periodic.bspline.basis’ now take an
          optional non-negative integer argument ‘deriv’.  When ‘deriv
          > 0’, the order-‘deriv’ derivative of each basis function is
          returned.

        • A new function, ‘periodic_bspline_basis_eval_deriv’, has been
          added to the C API.  This function gives access, at the C
          level, to evaluation of the derivatives of periodic
          B-splines.

        • Upgrade license to GPL version 3.

        • Fix buffer-flow problem identified by ‘valgrind’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_3:

        • Fix bug found by Eamon O'Dea in ‘gillespie.sim’.

        • Fix bug in ‘onestep.sim’.

        • The Ricker example has a new parameter, c, which scales the
          (unobserved) population size.  By default, c=1, so that the
          behavior is as before.

        • Improved error trapping.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_2:

        • Some changes have been made to the use of random numbers in
          some codes (the stochastic simulations in ‘gillespie.sim’ and
          the resampling in the particle-filtering codes).  These
          changes will mean that calculations performed before will not
          be reproducible in perfect detail, but will be statistically
          equivalent.

        • Minor changes in C codes to obviate warnings generated by T.
          Kalibera's ‘rchk’ checks.

        • The rare and fascinating “Bug of St. Patrick” has been fixed.
          Thanks to Carles Breto for finding the bug and helping to
          isolate it.

        • More informative error messages are generated when ‘dmeasure’
          returns a non-finite likelihood in any of the particle
          filtering codes.

        • Some streamlining of codes.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_1:

        • Callable routines are now registered.

        • The functions ‘bake’, ‘stew’, and ‘freeze’ now preserve
          information about the system time used in computation as an
          attribute of the returned object.  In addition, these
          functions store information about the RNG settings.

        • Some documentation improvements, courtesy of Sebastian Funk.

        • Various documentation improvements.

        • More verbosity is provided with ‘verbose=TRUE’.

        • Better handling of ‘pomp’'s ‘times’ argument.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._1_0:

        • New ‘logLik’ method for ‘pmcmcList’ objects.

        • The deprecated option to supply a matrix or numeric vector as
          the ‘data’ argument to ‘pomp’ have been removed and an error
          is now generated.  ‘data’ must be provided as either a data
          frame or an object of class ‘pomp’.  See ‘?pomp’ for details.

        • The deprecated ‘skeleton.type’ and ‘skelmap.delta.t’
          arguments to ‘pomp’ have been removed.  Using these arguments
          will now generate an error message.  The correct method of
          specifiying the deterministic skeleton is now explained in
          the help pages (‘?pomp’).

        • Source code fixes to eliminate warnings during compilation.

        • Improved test suite.

        • Minor documentation correction.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._9:

        • During particle filtering, when non-finite ‘dmeasure’ values
          are generated, an error is generated and the offending
          parameters, states, data, and time are reported.  In methods
          that use parameter transformations (‘transform=TRUE’), the
          reported parameters were on the transformed (estimation)
          scale, which can be confusing.  The error message now gives
          the parameters on the natural (model) scale.

        • Modified ‘src/ssa.c’ to fix UBSAN errors.

        • C codes have been modified to take advantage of changes to
          the R API (R SVN REVISION 71180).

        • A bug in ‘mif2’ arising when filtering fails in the final
          timestep has been fixed.  In this case, when all particles
          are deemed inconsistent with the data, we use an unweighted
          mean (with a warning) in place of the default weighted mean.

        • C codes have been modified to take advantage of changes to
          the ‘R’ API (R SVN REVISION 71180).

        • Modified ‘src/ssa.c’ to fix UBSAN errors.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._8:

        • There is a new option, ‘shlib.args’, to ‘pomp’.  This allows
          arbitrary options to be passed to the compiler when C
          snippets are used.  In particular, one can link a library of
          C snippets against a precompiled static library.

        • In Sobol' sequence generation (‘sobolDesign’,
          ‘profileDesign’), we now use the suggestion of Joe & Kuo
          (2003) to choose a better sequence start point.

        • The generation of Sobol' sequences (‘sobolDesign’,
          ‘profileDesign’) is now performed using the ‘NLopt’ routines
          written in C instead of the original TOMS 659 FORTRAN codes.
          The copyright notices are located in the source code.

        • The stochastic simulation algorithms underlying the Gillespie
          and K-leap methods (‘gillespie.sim’, ‘kleap.sim’) have been
          refactored in C.  In addition, errors due to accumulation of
          round-off error have been repaired.  The result will be more
          accurate, but somewhat slower when there are a very large
          number of reactions.

        • Fixed a bug in ‘plot’ on ‘pomp’ objects with more than 10
          variables to plot.

        • Added the ‘shlib.args’ option to ‘pomp’, allowing arbitrary
          options to be passed to the compiler when C snippets are
          used.

        • Modified the “dacca” example to use C snippets.

        • Refactored ‘rw.sd’ for greater stability.

        • Modified the “dacca” example to use C snippets.

        • Made Sobol' codes more robust.

        • Modified the demos to use best practices.

        • Further improvements to the test suite.  Code coverage is now
          100%.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._7:

        • Improvement of the test suite and of error messages.

        • Improve the ‘show’ and ‘print’ methods for ‘pomp’ objects.

        • Some internal refactoring.

        • Improve error messages for missing basic components.

        • Fix typos in one of the help-page examples.

        • Several obscure bug-fixes.

        • Add some references.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._6:

        • Major revisions to the package help pages and manual.  The
          separate documentation on C snippets and process-model
          plugins has been merged into the main ‘pomp’ help page, which
          now has comprehensive instructions on building a ‘pomp’
          object.

        • Update to the package help page.

        • New methods for the Ensemble Kalman Filter (‘enkf’) and
          Ensemble Adjustment Kalman Filter (‘eakf’) have been added to
          the package.

        • There is a new plugin for ‘rprocess’ called ‘kleap.sim’.
          This implements the so-called “K-leap method” of Cai & Xu
          (2007).

        • Major overhaul of error handling system and to error and
          warning messages.  Many more errors are now trapped and
          reported with more informative messages.

        • The matrix and numeric vector options for the ‘data’ argument
          to ‘pomp’ are now deprecated and will be removed in a future
          release.  In calls to ‘pomp’, ‘data’ should be either a data
          frame or a ‘pomp’-class object.

        • In ‘mif2’, it is now required that ‘Nmif>0’.

        • Redundant ‘bootstrap’ argument to ‘nlf’ has been removed.

        • Many improvements to the test suite to obtain better code
          coverage.

        • Fixed bugs that might arise in rare circumstances in
          ‘simulate’ and ‘eulermultinom’ functions.

        • Fixed a bug in ‘pompExample’.

        • Fixed several small, rare bugs found as a result of improved
          testing.

        • Fixed bug in specification of skeleton in pompExamples.

        • ‘pomp’ is no longer an S4 method.  Its new status as an
          ordinary function abbreviates and consolidates the code and
          simplifies the documentation.

        • Some minor improvements to error messages.

        • A bug restricting access in C code to ‘userdata’ has been
          fixed.

        • Fixed bug in ‘pompExample(...,show=TRUE)’.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._5:

        • A better interface for specifying a model's deterministic
          skeleton is provided.  One specifies
          ‘skeleton=map(f,delta.t)’ for a discrete-time skeleton (a
          map) and ‘skeleton=vectorfield(f)’ for a continuous-time
          skeleton (a vectorfield).  The old arguments ‘skeleton.type’
          and ‘skelmap.delta.t’ are deprecated and will be removed in a
          future release.

        • The ‘pfilter’ help page has been improved.  Specifically, the
          discussion of filtering failures is better.

        • Miscellaneous improvements to the help pages.

        • ‘mif2’ no longer computes filter means.

        • The new argument ‘show’ of ‘pompExamples’ allows one to
          display the example code instead of executing it.

        • The minimum version of R supported is now 3.1.2.

        • ‘init.state’ now has the optional argument ‘nsim’.  Using
          this, one can request multiple initial state vectors per
          parameter vector.

        • ‘pfilter’ now uses less memory when it is asked to run at a
          single point in parameter space.

        • A bug associated with the ‘rw.sd’ argument to ‘mif2’ on
          Windows platforms has been fixed.

        • The ‘method="mif2"’ option to ‘mif’ has been removed.  Use
          ‘mif2’ instead.

        • The ‘particles’ method (rarely if ever used), has been
          removed to streamline the ‘mif’ codes.

        • The ‘method="mif2"’ option to ‘mif’ is now deprecated.  It
          will be removed in a future release.  Use ‘mif2’ instead.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._4:

        • Following the publication of the Journal of Statistical
          Software announcement paper, the ‘CITATION’ has been modified
          to include the appropriate citation.  Please use
          ‘citation("pomp")’ to learn about how to cite ‘pomp’
          correctly.

        • ‘conv.rec’ on the results of a ‘mif2’ computation now play
          nicely with ‘reshape2::melt’.

        • It is now possible to direct ‘pomp’ to place ‘Csnippet’ codes
          in a specified location.  This is accomplished via the new
          ‘cdir’ and ‘cfile’ arguments to ‘pomp’.

        • When several concurrent R processes attempt to simultaneously
          compile ‘Csnipet’ code from copies of a ‘pomp’ object on the
          same machine, a race condition exists.  This release fixes
          this by ensuring that ‘Csnippet’ codes are written and
          compiled in a process-specific directory.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._3:

     This release removes several long-deprecated features.

        • The ‘seed’ argument to ‘pfilter’ has been removed.  Use
          ‘freeze’ to obtain similar functionality.

        • The redundant ‘pars’ argument to ‘mif’ has been removed.
          Names of parameters to be estimated are taken from the
          nonzero entries of ‘rw.sd’.  Initial-value parameters are
          designated using the ‘ivps’ argument.

        • The old ‘parameter.transform’ and ‘parameter.inv.transform’
          arguments to ‘pomp’ have been removed.  They were superseded
          by the arguments ‘fromEstimationScale’ and
          ‘toEstimationScale’ in version 0.65-1.

        • Some internal changes to ‘mif2’ by C. Breto, in support of
          panel methods under development.

_C_h_a_n_g_e_s _i_n '_p_o_m_p' _v_e_r_s_i_o_n _1._2:

        • Bug fix: for POMPs with a scalar state variable, the
          ‘filter.mean’, ‘pred.mean’, and ‘pred.var’ methods dropped
          the singleton dimension of the respective arrays, in conflict
          with the assumptions of certain ‘plot’ methods.  This
          resolves issue #3.

        • Documentation improvements.  Specifically, the details of how
          step-sizes are chosen in the ‘euler.sim’,
          ‘discrete.time.sim’, and ‘onestep.sim’ plugins has been
          spelled out explicitly.  Also, incompleteness in the
          ‘sannbox’ documentation has been corrected.

        • Provide ‘filter.traj’ method for ‘pmcmcList’ objects.

        • Fixed a bug in ‘mif’ and ‘mif2’ when
          ‘cooling.type="hyperbolic"’ and ‘cooling.fraction.50=1’.

